Mark a line 3 inches in from each end of the keyboard tray where the drawer front will be attached using a tape measure and a pencil.
Place the angle brackets on the keyboard tray so that half of the bracket can be mounted on the keyboard tray and the other half mounted to the drawer front.
Fasten both brackets to the keyboard tray and the mark using a power drill and grabber screws.
Hold the drawer front into position on the keyboard tray. Fasten the drawer front to the keyboard tray using grabber screws through each angle bracket.